For this lab, you need:
- Google Earth
- A browser with Adobe Flash Player
- The ability to access videos online
An Introduction to Ecological Succession
Ecosystems are always changing. Ecologists and geographers are interested in this change. Is the change beneficial or harmful? To which species? Can we predict what an ecosystem will look like in the future? Succession is how ecosystems form and change over time. Succession comes in two types:
- Primary succession: where there is no ecosystem and no soil, so life is starting from “scratch” in an area.
- Secondary succession: where an ecosystem has been disturbed, from something as small as a falling tree, to something as big as a forest fire, but the soil remains intact.
Please watch this video that’s just over 10 minutes about ecological succession.
CrashCourse Ecology #6: Ecological SuccessionEcological Succession: Change is Good – Crash Course Ecology #6 (链接到外部网站。)
Primary Succession: Two Explosive Islands
Volcanic activity is one of the most common ways to find examples of primary succession. New land has formed, but there isn’t any soil yet. In 2017, a new island formed in Tonga between two existing islands.
Please watch this 5 minute video about the birth of a new island:
From 1963-1967, another new island formed in a similar way off the southern coast of Iceland. While we may speculate about what may happen to Hunga Tonga Hunga Ha’apai, we can see what has happened to Surtsey over 50 years later.
Go to this website to read about Surtsey, and the first life that took hold there:
Use Google Earth to look at both islands. You can find them using these coordinates:
Surtsey: 63.30N, 20.20W
Hunga Tonga – Huya Ha’apai: 20.54S, 175.39W
Please answer the following questions.
- Use the coordinates provided and the map in your atlas to find the climate type for each of these islands using the Koppen Climate Classification System. List and briefly describe the climate type for both islands.
- Based on the climate type, what may be some different limiting factors for primary succession for the two different places?
- Hunga Tonga Huya Ha’apai formed between two existing islands joining them, while Surtsey island formed in isolation. How might this affect the succession of these two places?
- Surtsey has existed now for 50 years, and has some life on it. According to the materials provided, what was some of the first life to come to Surtsey, and how did it get there?
- You have been given funding to study primary succession at these two sites. Come up with a research question you would like to answer, and find at least one method you could use to try to answer your question. Please cite any sources you use.
Secondary Succession: Clearcutting
Secondary succession looks a how an ecosystems forms after a previous ecosystem suffered some sort of disturbance. This can be something natural, like a fire, or cause by humans, like the example we will look at: clearcutting. Soils exist, so don’t need to be formed from scratch, but there is no guarantee that the ecosystem that replaces the old on will be of the same type that was disturbed.
Clearcutting is a logging practice where a whole area of trees is cut at the same time, and often replanted with a monoculture of new trees. This is a very efficient, but highly controversial logging practice, so let’s take a look at some of the impacts and controversy around this practice.
A very powerful tool used to study forest health is satellite imagery and remote sensing. One very cool thing about these sensors is that they can see types of light human eyes cannot. Near Infrared light is not visible to human eyes, but plants give off a ton of it when they are making food with photosynthesis. You can read more here:
Reflected Near-Infrared Waves, NASA: https://science.nasa.gov/ems/08_nearinfraredwaves
The two images below are of forest clearcutting in Washington State using reflected near-infrared light. Areas of more near-infrared light are in green, and areas with less are in red. Green areas have the most healthy vegetation, and red areas the least. You can get a good idea about clearcutting and regrowth in an area by comparing these images:
Source: Logging and Regrowth in Washington State, NASA Earth Observatory. July 5, 2011, viewed March 4, 2019. https://earthobservatory.nasa.gov/images/51257/log…
You can see the full images below.
Next, open Google Earth, and go to Mt. Rainier, Washington. You can see Mt Rainier in the bottom left corner of the full sized images. Zoom out in Google Earth until you are in the same extent at the satellite photos. The picture on Google Earth is different, because it shows the area in visible light, instead of near IR light like the previous images. Areas here with healthier forests are darker green, and the more brown, the less vegetation.
7. Describe what you see in the Google Earth image forest cover compared to the images from 1984 and 2010. How have things changed? What looks the same? Make sure to talk about both regrowth areas and unlogged areas.
Pros and cons
Please explore these two websites about clearcutting. The first is from a logging advocacy group, and is very pro-clearcutting. The second is from a non-profit that is trying to end the practice.
Oregon Forest Resources Institute: https://oregonforests.org/clearcutting (链接到外部网站。)
Stop Clearcutting California: https://www.stopclearcuttingca.org/about-clearcutting/what-is-clearcutting/ (链接到外部网站。) (make sure to look at the different sections, you can see the table of contents to the right. You must look at the first page, and “What’s wrong with it?”.)
Please answer the following questions:
8. After looking through the material, briefly list some pros and cons to clearcutting.
9. You have the means to try and settle part of the argument over clearcutting. Select one of the concerns people have about clearcutting, and design a way to test if the concern is accurate or not. Please do some research of real methods scientists use to collect this kind of data, and cite your sources.
Invasive Species: Zebra Mussels
One of the concerns about man made disturbance is that it provides opportunities for invasive species to take over an ecosystem. An invasive species is a non-native lifeform that moves into an area and causes damage to the area’s diversity and overall health. Invasive species can be a very serious problem. We will look at one of these species that has cause both economic and ecological harm in the US, the Zebra Mussel.
Please watch this short video about zebra mussels and their impact on lakes in the US:“Silent Invaders” Zebra Mussels 2013 (链接到外部网站。)
Use the graph below to answer the following questions:
Densities of zebra mussels and unionid mussels are given in number per square meter, averaged over the freshwater tidal Hudson (RKM 99-248); data collected in August for zebra mussels and July for unionids. Scientists began collected unionid data in 1991. One meter squared equals ten square feet.
Source of both graphs: Michelle Smith, Zebra Mussel Graphing Exercise, BIO 124 Lab, Windward Community College. Accessed 3/4/2019, https://windward.hawaii.edu/facstaff/miliefsky-m/B…
11. Record the density of zebra mussels and unionid mussels for the following years: 1992, 1997, 2004. Please note: The density for zebra mussels is labeled on the left, and the unionids is on the right side of the graph.
12. How did the native unionid mussel density change over this time period?
13. How did the zebra mussel density change over this time period?
Effect on Food Sources
To understand the effect the zebra mussels may have had on the food supply, we first need to look at predator and prey relationships. Please go to the following website to explore how populations of predators and prey affect each other: http://www.phschool.com/atschool/phbio/active_art/predator_prey_simulation/index.html (链接到外部网站。)
Please note: You will need adobe flash player to do this activity.
The graph below shows the relationship between zebra mussel populations and their food supply, phytoplankton. Use what you learned about predatory/prey relationships and the graph below to answer the following questions.
14. What are the phytoplankton population density for 1992, 1997, and 2004?
15. Compare the relationship between phytoplankton density and zebra mussels. What patterns do you see?
16. Give an overview of how you think zebra mussels have affected both native mussels and phytoplankton on the Hudson river based on this data. Please support your discussion with data and evidence.